With reference to FIG. 6, a conventional blocking structure of an anti-fire door lock 400 comprises a latch set 410 and a blocking base 420, wherein the latch set 410 is mounted on an anti-fire door 500, and the blocking base 420 is mounted on a door frame 600. The latch set 410 comprises a main body 411, a latch 412 and a linking set 413, and wherein the latch 412 pivotally connects to the main body 411. The latch 412 is able to protrude to the main body 411 or retract in the main body 411 selectively by the linking set 413 to make the anti-fire door 500 being opened or closed relative to the door frame 600. The latch 412 comprises a blocking surface 412a, and wherein the blocking surface 412a contacts against the blocking base 420 to prevent the anti-fire door 500 from being opened when the latch 412 protrudes to the main body 411. Oppositely, the blocking base 420 can not constrain the latch 412 when the latch 412 retracts in the body 411, therefore, the anti-fire door 500 is able to be opened.
With reference to FIG. 6, the anti-fire door 500 is deformed because the elevation of environmental temperature while a fire accident occurs, and the latch set 410 produces displacement relative to the blocking base 420 at the same time. The anti-fire door 500 is able to be opened and is unable to achieve the function of fire excluding when the latch 412 is displaced to make the blocking surface 412a unable to contact against the blocking base 420.